Spasmodic refers to involuntary muscular contractions or to any action occurring in abrupt, irregular fits. In accounts of disease, it may describe coughing, trembling, convulsions, pain, or disrupted breathing, giving the body a sense of lost control. Poets use the term to represent literal illness as well as emotional shock, panic, rage, or grief that breaks through composed speech. Its uneven rhythm is especially useful in poetry, where spasmodic movement can shape a line, voice, or image into an experience of strain and interruption.

"Spasmodic" describes sudden, violent, involuntary muscle contractions—or figuratively, irregular, erratic bursts of energy and emotion. In 19th-century literary history, the "Spasmodic Poets" (a group including Alexander Smith and Sydney Dobell) were known for their intense, emotionally turbulent, and unstructured verse. Teaching this term allows instructors to introduce both the general metaphor of convulsive emotion and a specific historical poetic movement defined by dramatic, feverish intensity. Related terms include convulsive, fitful, paroxysmal, and erratic.